Durable, heat resistant, erasable release coatings, release coated substrates, and their methods of manufacture

ABSTRACT

Methods are generally disclosed for forming and using a release sheet. To form the release sheet, a release coating is applied over a first surface of a base sheet. Generally, the release coating includes a fatty alcohol ester of acrylic acid and a curable monomer, and can also include a curable polymeric resin. Then, the release coating can be cured. In one particular embodiment, the release coating can be substantially free from siloxanes. The release sheet formed according to this method is also generally provided, along with methods of forming a casting sheet using the release sheet are also generally provided.

BACKGROUND OF THE INVENTION

Release coatings used in durable, stain resistant, heat resistant orerasable materials as well as in release papers typically includesilicone containing materials or other release agents to provide therelease properties. However, the silicone groups, and particularlysiloxane groups (e.g., PDMS, organo-silicones, reactive silicones likeacrylate functional materials, etc.), in typical silicone releasecoatings can lead to severe contamination problems. Since the typicalsiloxane release agents in coatings are present as low molecular weightmaterials before curing, at this stage they are not anchored into thecoating and can transfer to coating equipment and then to othermaterials subsequently processed on the equipment. The siloxane releaseagents have a low surface tension and low viscosity and thus tend toeasily spread onto the equipment and then onto other materials processedon the equipment. This contamination is difficult to remove andcontaminated materials such as films or papers contaminated with thesiloxanes have very low surface energy spots which cause voids incoatings applied to them and poor adhesion of coatings, inks oradhesives. Once the coatings are cured, the siloxanes should be firmlyanchored; however, the cured silicone release coatings have anotherdisadvantage: in certain applications, it is desirable to apply inks orother coatings onto the release coatings and then remove such inks orcoatings sometime later. For example, one might want to apply a coatingor an ink to the release coating and then transfer the coating or ink toanother material such as a garment at a later date, or one might want touse the release coating as an erasable substrate. However, due to thevery low surface energy of typical siloxane containing release coatings,subsequently applied coatings or inks will not spread evenly and tend tobead on the surface. Additionally, coatings containing silicone releaseagents cannot be conveniently coated with water based acrylic orpolyurethane polymers due to the low surface energy of these releasecoatings.

Although siloxane containing release coatings do pose problems, they arevery effective and their effectiveness in many applications has not beenmatched by other types of release coatings. Thus, a need exists foreffective durable, heat resistant and erasable release coatings whichcontain no siloxane release agents. Additionally, a need exists forrelease coatings which can be effectively printed or over coated withinks or coatings which are subsequently removable. Also, there is a needfor durable, graffiti resistant and erasable materials. In addition,heat transfer papers and heat transfer decals which have internalrelease coatings and releasably attached polymeric coatings, such aspolyurethane and acrylic polymer coatings, are desired for transfer ofdurable, stretchable graphics and also for transfer of textures.

SUMMARY OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

To form a release coated substrate, the release coating can be appliedover a first surface of a substrate. Generally, the release coatingincludes a fatty alcohol ester of acrylic acid (e.g., lauryl acrylate)and a curable monomer (e.g., trimethyloipropane triacrylate). In certainembodiments, a curable polymeric resin can also be included in therelease coating. Then, the release coating can be cured (e.g., viaexposing the release coating to e-beam radiation). The release coatingcan be substantially free from siloxane release agents (e.g.,substantially free from release agents having siloxane groups).

The release coated substrate formed according to this method is alsogenerally provided. Also provided are release sheets with heattransferable images, heat transfer papers with a print coatingoverlaying a release coating, and a paper or film useful for casting ofthermoplastic coatings onto substrates such as leather and fabrics.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof to one skilled in the art, is set forth moreparticularly in the remainder of the specification, which includesreference to the accompanying figures, in which:

FIG. 1 shows a release coated substrate with an exposed release coatingaccording to one exemplary embodiment of the present invention;

FIG. 2 shows a release sheet including a base sheet with an exposedrelease coating according to another aspect of this invention;

FIG. 3 shows formation of a patterned release surface of a releasecoating overlying a back sheet and conforming to the patterned surfaceof a forming roll during cure of the release coating to form a patternedrelease substrate;

FIG. 4 shows the release sheet of FIG. 2 having a patterned surface;

FIG. 5 shows a thermoplastic layer applied over the release sheet ofFIG. 4;

FIGS. 6-7 sequentially show an exemplary heat transfer for transferringthe thermoplastic layer of FIG. 5 to a substrate;

FIG. 8 shows a heat activate-able image applied to the release paper ofFIG. 2;

FIGS. 9 and 10 sequentially show transfer of the heat activate-ableimage of FIG. 8 to a substrate;

FIG. 11 shows a meltable print coating applied to the release paper ofFIG. 2;

FIG. 12 shows an image printed onto the print coating of FIG. 11;

FIGS. 13 and 14 sequentially show transfer of the printed image of FIG.12 to a substrate;

FIG. 15 shows an erasable paper with a printed image on one surface ofthe paper and a release coating overlying the printing;

FIG. 16 shows an erasable translucent paper with a printed image on oneside and a release coating on the other side;

FIG. 17 shows a heat sealable protective substrate with a heat sealableadhesive on one side and a release coating on the other side; and

FIG. 18 shows the application of the heat sealable protective substrateof FIG. 17 to a substrate.

Repeat use of reference characters in the present specification anddrawings is intended to represent the same or analogous features orelements of the present invention.

DEFINITIONS

The term “molecular weight” generally refers to a weight-averagemolecular weight unless another meaning is clear from the context or theterm does not refer to a polymer. It long has been understood andaccepted that the unit for molecular weight is the atomic mass unit,sometimes referred to as the “dalton.” Consequently, units rarely aregiven in current literature. In keeping with that practice, therefore,no units are expressed herein for molecular weights.

As used herein, the term “cellulosic nonwoven web” is meant to includeany web or sheet-like material which contains at least about 50 percentby weight of cellulosic fibers. In addition to cellulosic fibers, theweb may contain other natural fibers, synthetic fibers, or mixturesthereof. Cellulosic nonwoven webs may be prepared by air laying or wetlaying relatively short fibers to form a web or sheet. Thus, the termincludes nonwoven webs prepared from a papermaking furnish. Such furnishmay include only cellulose fibers or a mixture of cellulose fibers withother natural fibers and/or synthetic fibers. The furnish also maycontain additives and other materials, such as fillers, e.g., clay andtitanium dioxide, surfactants, antifoaming agents, and the like, as iswell known in the papermaking art.

As used herein, the term “polymer” generally includes, but is notlimited to, homopolymers; copolymers, such as, for example, block,graft, random and alternating copolymers; and terpolymers; and blendsand modifications thereof. Furthermore, unless otherwise specificallylimited, the term “polymer” shall include all possible geometricalconfigurations of the material. These configurations include, but arenot limited to isotactic, syndiotactic, and random symmetries.

The term “thermoplastic polymer” is used herein to mean any polymerwhich softens and flows when heated; such a polymer may be heated andsoftened a number of times without suffering any basic alteration incharacteristics, provided heating is below the decomposition temperatureof the polymer. Examples of thermoplastic polymers include, by way ofillustration only, polyolefins, polyesters, polyamides, polyurethanes,acrylic ester polymers and copolymers, polyvinyl chloride, polyvinylacetate, etc. and copolymers thereof.

In the present disclosure, when a layer is being described as “on” or“over” another layer or substrate, it is to be understood that thelayers can either be directly contacting each other or have anotherlayer or feature between the layers (unless otherwise stated). Thus, forexample as shown in the figures and described in the accompanyingdescriptions, these terms are simply describing the relative position ofthe layers to each other and do not necessarily mean “on top of” sincethe relative position above or below depends upon the orientation of thestructure to the viewer.

In this discussion, the term “release coating” indicates a coating whichhas release properties for a number of materials and is durable. Amaterial which “has release properties for a second material” means herethat the second material can be removed from the first, releasematerial, easily and without damage to either the release material orthe second material.

An “erasable” material refers to a material which will accept ink, butallows the ink to be removed without substantial damage to the material.

A “graffiti resistant material” means that the material can be cleanedafter it has been defaced by ink, paint, lipstick, food and othermaterials which might otherwise cause permanent defacement.

The term “substrate” refers a material to which coatings can be appliedand, as such, encompasses a wide variety of materials.

DETAILED DESCRIPTION

It is to be understood by one of ordinary skill in the art that thepresent discussion is a description of exemplary embodiments only, andis not intended as limiting the broader aspects of the presentinvention, which broader aspects are embodied in the exemplaryconstruction.

Generally speaking, coating compositions which contain no siloxanerelease agents and which can be applied to a variety of substrates, thencured to form durable, heat resistant release surfaces on thesesubstrates are provided. Additionally provided are release papers,casting papers, erasable papers and printable heat transfer papers. Alsoprovided are durable, graffiti resistant surfacing materials which canbe bonded to surfaces not conveniently coated with the curable releasecoatings.

In various embodiments, the coating can be applied to substrates whichthen function as durable materials, heat resistant release substrates,graffiti resistant materials, erasable materials, stain resistantmaterials and heat transfer materials.

Methods are also generally disclosed for using the release coating on anumber of substrates for many applications. These include release papersfor application and transfer of graphics, release papers and films forrelease of pressure sensitive labels and tapes and erasable films andpapers for toys, games, posters and note pads and also durable, easilycleanable coatings on items such as floors, table tops, wall panels andthe like. In many applications, the coating can be applied directly tothe substrate. In cases where this is not convenient, it is envisionedthat the coating can be applied to a film or paper with a heat activatedadhesive or a pressure sensitive adhesive which can then be bonded to asecond substrate which is not conveniently coated directly.

The high heat resistance and reusable qualities of the release coatingstem from a highly crosslinked polymeric material formed upon curing therelease coating. The release coating generally includes a fatty alcoholester of acrylic acid, a curable polymeric resin, and a curable monomer.Additionally, materials which are useful in mixing and applying thecoatings such as defoamers, rheology control agents, fillers andsurfactants may be employed if needed in the coating process providedthat such materials do not materially affect the critical surfacetension of the cured coatings or the release properties. Also, some ofthese useful additives used in small amounts to control the aboveprocessing properties may contain siloxane groups, provided that theyare not siloxane release agents.

The release coating can contain from about 5% to about 60% of an acrylicacid ester of a fatty alcohol, also called a long chain hydrocarbonalcohol. Without wishing to be bound by any particular theory, it isbelieved that the fatty alcohol ester of acrylic acid provides releaseproperties to the release layer without the addition or presence ofsilicone polymers or other release agents (eg, waxes etc.).

In one particular embodiment, the release coating is substantially freefrom siloxane release agents, such as substantially free from releaseagents having siloxane groups. As used herein, the term “substantiallyfree” means no more than an insignificant trace amount present andencompasses completely free. For example, in one embodiment, the releasecoating can consist essentially of the fatty alcohol ester of acrylicacid, the cured polymeric resin, and the curable monomer such that therelease coating is substantially free from other compounds.

Without wishing to be bound by any particular theory, it is believedthat the absence of siloxane release groups in the release coatingallows the release coating to be over coated with water-based and otherrelatively high surface tension coatings without defects caused by poorwetting; yet will allow these coatings to release easily from therelease coating, even after being subjected to pressure and heating to375° F. or higher. One way to measure the ease of wetting surfaces witha liquid is to spread a liquid of known surface tension on the surface,then observe whether the liquid forms a continuous film on the surfaceor separates into droplets. For example, one may use Accu Dyne® testpens from Diversified Enterprises (Claremont, N.H.), who provide a setof pens with a range of surface tensions. The “critical surface energy”of the surface is equal to or nearly equal to the surface tension of thelowest surface tension liquid which wets evenly. Thus, liquids with asurface tension less than about the measured critical surface energywill wet the surface evenly.

The fatty alcohol ester of acrylic acid generally includes an acrylicgroup attached via an ester linkage to a hydrocarbon chain. The acrylicgroup is generally polymerizable and can include an acrylic moiety, amethacrylic moiety, etc. The hydrocarbon chain of the fatty alcohol canbe of any length, such as comprising from about 8 to about 26 carbons,for example from about 12 to about 22 carbons. Alternatively, in otherembodiments, the hydrocarbon chain can comprise from about 18 carbons toabout 26 carbons. For instance, in one particular embodiment, the fattyalcohol can have a hydrocarbon chain of 18 carbons.

The hydrocarbon chain on the fatty alcohol ester of acrylic acid can beeither saturated or unsaturated including both monounsaturated andpolyunsaturated fatty alcohols. A saturated carbon chain means that allthe carbon to carbon bonds in the hydrocarbon chain are single bonds,allowing the maximum number of hydrogen atoms to bond to each carbon,thus the chain is “saturated” with hydrogen atoms. An unsaturatedhydrocarbon chain means that the carbon chain contains at least onecarbon to carbon double bond, thereby reducing the number of hydrogenatoms present on the chain. A monounsaturated hydrocarbon chain containsone carbon to carbon double bond, while a polyunsaturated hydrocarbonchain contains at least two carbon to carbon double bonds.

Many fatty alcohol chains have common names, relating to theircorresponding hydrocarbon chain, to describe the chain. The hydrocarbonchains can also be described by the number of carbon atoms present inthe chain and the number and location of any double bonds present in thechain, represented by x:y^(Δp,p′,p″), where x is the number of carbonsin the hydrocarbon chain, y is the number of carbon to carbon doublebonds in the chain, p is the location of the first double bond (ifpresent), p′ is the location of the second double bond (if present), p″is the location of the third double bond (if present), and so on.

In one particular embodiment, the fatty alcohol ester of acrylic acidcan include a saturated hydrocarbon chain. Examples of saturated fattyalcohols that can be used as the fatty alcohol ester of acrylic acidinclude, but are not limited to, lauryl alcohol (12:0), tridecyl alcohol(13:0), myristil alcohol (14:0), pentadecyl alcohol (15:0), cetylalcohol (16:0, also known as palmityl alcohol), heptadecyl alcohol(17:0), stearyl alcohol (18:0), arachidyl alcohol (20:0), and behenylalcohol (22:0).

For example, the fatty alcohol ester of acrylic acid with a saturatedhydrocarbon chain can generally be defined by Formula 1:

where n is an integer between 6 and 20. As such, the hydrocarbon chaincan have a total length of 8 to 22 carbons. For example, when n is 10,the resulting compound shown in Formula 1 is lauryl acrylate.

The relative amounts of the components (i.e., the fatty alcohol ester ofacrylic acid, the curable polymeric resin, and the curable monomer) canbe adjusted to form the desired release properties in the releasecoating. However, in one particular embodiment, the release coating caninclude the fatty alcohol ester of acrylic acid in an amount of about 5%to about 50% by weight of the release coating prior to curing (e.g.,about 10% to about 25% by weight). The release coating can include thecurable polymeric resin in an amount of about 0% to about 80% by weightof the release coating prior to curing (e.g., about 30% to about 50% byweight). The release coating can include the curable monomer in anamount of about 15% to about 60% by weight of the release coating priorto curing (e.g., about 30% to about 50% by weight).

The curable monomer is selected to react with the curable polymer andthe fatty alcohol ester of acrylic acid to form a highly crosslinkedrelease coating. For example, the curable monomer can includetrimethylolpropane triacrylate (TMPTA), which is a trifunctional monomerwith a relatively low volatility and fast cure response. Due to thetrifunctionality of this monomer, the resulting cured polymeric materialis highly crosslinked, resulting in high heat resistance and a durablerelease coating.

The curable polymers may include, but are not limited to, epoxyacrylates, polyurethane acrylates, polyester acrylates and other curableresins with double bonds (e.g., vinyl moieties). It is understood thatthe multifunctional monomers in these formulations are required toprovide crosslinking which imparts heat resistance, solvent resistanceand durability. The amount of crosslinking increases as the equivalentweight of the monomer decreases and as the number of reactive sites permolecule increases. It is probable that only about 10% of very efficientmonomers such as tetrafunctional monomers would be needed, whereas up to80% of some of the high equivalent weight difunctional monomers may berequired.

Curable resins in these release coating formulations can provideincreased viscosity before curing and attributes in the cured coatingssuch as flexibility, hardness, toughness, weather resistance etc. Theincreased viscosity is desirable for coating of relatively porousmaterials, since more viscous coatings will remain on the surface for alonger time (eg. until the coating is cured). The percentage of curableresin, such as Ebecryl37-20T, needed in the present formulations isanticipated to be zero or near zero if the substrate is not porous.

The release coating is cured after application to its support material(e.g., the substrate or a base sheet, as discussed in greater detailbelow). Curing generally transforms the curable polymeric resin into ahighly crosslinked layer configured to withstand multiple heating andpressing cycles encountered during repeated use as a casting paper, aswell as repeated steps of marking the paper and erasing in erasableapplications and resistance to stains and solvents in graffiti resistantand durable applications.

In one embodiment, the release coating can be cured via a non-thermalcuring process. For example, the release coating can be exposed to ane-beam curing process or an UV curing process. Electron beam (e-beam)curing is a non-thermal curing process that generally involves exposingthe curable material to a stream of electrons (e.g., using a linearaccelerator). UV curing is a non-thermal curing process that generallyinvolves exposing the curable material to electromagnetic radiationhaving a wavelength in the ultra-violet range (e.g., about 10 nm toabout 400 nm). The curing process can be configured to produce thedesired degree of crosslinking in the release coating by altering theamount of energy supplied to the cured layer (e.g., by adjusting thetime the release coating is exposed to the curing process). The releasecoating may also be cured in a thermal process. If thermally cured, athermal cure initiator is needed. This is generally a chemical whichproduces free radicals when heated.

If desired, the release coating may be dispersed or dissolved in anorganic solvent or water. The coating is then dried before curing bymeans of, for example, steam-heated drums, air impingement, radiantheating, or some combination thereof.

The release coating may have a layer thickness selected according to theuse of the coated substrate. For applications requiring only releaseproperties and durability, the thickness can be only 1 to 10 microns.However, if desired, as, for example, in the case of patterned castingapplications, the coating can be up to 150 microns thick (as thick as isneeded to control the amount of texturing to be formed in thethermoplastic layer on the final substrate). For most applications, therelease coating has a thickness of about 1 μm to about 35 μm.

The release coating requires curing to convert it into a highlycrosslinked structure needed for release properties and durability.Curing via an electron beam requires no more components in the coatingother than the fatty alcohol ester of acrylic acid and the curablemonomer, although some curable resin such as an epoxy acrylate resin isdesirable. No initiator is required for electron beam curing since freeradicals which initiate the curing are generated when the electronscollide with the materials in the coating. As is well known in the artof formulating UV curable coatings, a photoinitiator is required if thecoating is to be cured with UV radiation. The photoinitiator producesfree radicals when it absorbs ultraviolet light. For thermal curing, asis well known in the art formulating thermally curable coatings, aninitiator which forms free radicals when heated is required.

As stated, the release coatings can be utilized with a variety ofsubstrates and application methods.

I. Release Coated Substrates

Referring to FIG. 1, a substrate 12 is shown having a release coating 16on its surface 14. The release coating 16 contains a cured coatingderived from at least a fatty alcohol ester of acrylic acid and a secondcurable monomer, and desirably includes a cured resin, as discussedabove.

The substrate 12 can include any article in which one wants to protectfrom applied compositions including, but not limited to, stains,graffiti, paints, inks, food, adhesives and other materials which woulddeface the article. The substrates 12 include, but are not limited to,flooring, wall panels, furniture, furniture components, food packages,cooking containers and erasable films and papers which can be used,erased and used again.

Methods of applying the release coating 14 will depend mainly on thesubstrate 12 and include, but are not limited to gravure, offsetgravure, flexographic press, offset press, roll, air knife, brush, meyerrod, silk screen and roller. For example, as is well known in the art,flat, uniform materials such as paper and film can be readily coatedwith gravure, offset gravure, wire wound rod, air knife, offsetlithographic press, and air knife methods. Materials which are notreadily rolled up such as furniture panels, glass panels, wail panels,wood and furniture components can be coated with a brush, spray, roller,or a silk screen.

The curing method employed also depends on the nature of the substrate12. For example, many low melting materials such as plastics cannot becured conveniently with heat, whereas heat or UV curing is better formaterials which require a portable curing unit. (Electron beam curingunits are large and not easily transported so they are better suited tocuring of materials which can be transported to them, such as materialswound into rolls.) Also, as mentioned above, UV curing requires aphotoinitiator in the coating and thermal curing requires a thermallyinitiated curing agent in the coating.

II. Release Coated Sheets

Referring to FIG. 2, a release sheet 18 is shown including a base sheet20 (e.g., a paper, film, etc.) having a cured release coating 16 on itsfirst surface 24. The release coating 16 contains at least a cured fattyalcohol ester of acrylic acid a second cured monomer and desirablycontains a cured resin such as an epoxy ester resin, as discussed above.In certain embodiments, the release coating 16 generally does not meltor become tacky when heated. This quality is especially useful forapplications such as casting papers and cooking papers which aresubjected to heat.

A variety of methods may be used to apply the release coating 16 to thebase sheet 20. Curing may be done in a thermal process, via UV radiationor via electron beam radiation. No initiator is needed for the electronbeam curing; a photoinitiator is needed for UV curing whereas athermally initiator is needed for thermal curing. The release paper orfilm can be used in a wide variety of applications, included, but notlimited to, release liners for pressure sensitive adhesives, releasepapers and films for composites (such as epoxy/carbon fiber composites),release papers or films which can be coated with adhesives on thebackside to form tapes, release papers for food wrapping and cooking andfilms and papers for casting of thermoplastics.

FIG. 2 generally includes a base sheet 20 that acts as a backing orsupport layer. The base sheet 20 is flexible and has a first surface 24and a second surface 26. For example, the base sheet 20 can be a film ora cellulosic nonwoven web. In addition to flexibility, the base sheet 20also provides strength for handling, coating, sheeting, other operationsassociated with the manufacture thereof, and for removal afterembossing. The basis weight of the base sheet 20 generally may vary,such as from about 30 to about 150 g/m². Suitable base sheets 20include, but are not limited to, cellulosic nonwoven webs and polymericfilms. A number of suitable base sheets 20 are disclosed in U.S. Pat.Nos. 5,242,739; 5,501,902; and U.S. Pat. No. 5,798,179; the entirety ofwhich are incorporated herein by reference.

Desirably, the base sheet 20 comprises paper formed from a cellulosicmaterial. A number of different types of paper are suitable for thepresent invention including, but not limited to, litho label paper,publication paper, and barrier coated latex saturated papers.Penetration of the release coating 16 into the base sheet 20 isgenerally not desirable since a thicker coating would then be needed inorder to form a continuous release coating surface. Thus, the porosityof the base sheet 20 before coating should be very low. The Sheffieldporosity measurement is useful determining how well the substrate willhold a coating on the surface. In this technique, air is forced througha given area of the substrate and the flow rate of the air which passesthrough is measured in cubic centimeters per minute. Papers withSheffield porosities less than 25 are therefore preferred. Generally,this low porosity is not obtainable in papers unless they are coated,but most films and coated papers are sufficiently non-porous forapplication of the release coatings. The base sheet 20 is readilyprepared by methods that are well known to those having ordinary skillin the art.

The release coating 16 is coated over the first surface 24 of the basesheet 20, and coated such that substantially all of the first surface 24is covered by the release coating 16.

III. Casting Papers

In one particular embodiment, the release coating 16 is cured whilebeing held against a forming roll such that surface 17 of the releasepaper 16 retains the shape imparted by the forming roll after it iscured. For example, the release coating 16 may be patterned in order toimpress a pattern into thermoplastic materials in a casting process.

Referring to FIG. 3, for example, the release coating 16 can be appliedto the base sheet 20. The uncured release coating 16 can then be pressedagainst a patterned surface 33 of a forming roll 32 while it is cured(e.g., shown as a nip 34 formed between the patterned forming roll 32and the pressure roll 36). As such, a patterned surface 17 is formed inthe cured release coating 16 on the base sheet 20, as shown in FIG. 4.As shown, the patterned surface 17 defines a series of peaks 10 andvalleys 11 to impart a texture; however, any pattern, design, image,etc. can be formed in this manner.

In one particular embodiment, the patterned release sheets 18 can beused as casting papers for transfer of thermoplastic or thermosetcoatings to substrates such as cloth and leather. Such thermoplasticcoatings provide desired appearances as well as durability to these andsimilar substrates. Referring to FIG. 5, the release sheet 18 of FIG. 4(called a casting paper in this use) is coated with a thermoplasticcoating 28 (e.g., polyvinyl chloride, a polyurethane, etc.).

FIGS. 6 and 7 depict transfer of the thermoplastic coating 28 to asubstrate 30. Specifically, the thermoplastic coating 28 is placedadjacent to the substrate 30 (i.e., in direct contact), and heat (H) andpressure (P) are applied to the second surface 26 of the base sheet 20.Accordingly, the thermoplastic coating 28 melts and attaches to thesubstrate 30, while retaining a patterned surface 29 that is a mirrorimage to the patterned surface 17 of the release coating 16. The releasesheet 18, via its release properties of the release coating 16, then canbe peeled from the thermoplastic coating 28. In this use, good releaseof the thermoplastic coating, heat resistance and durability of thecasting paper 18 and the release coating 16 are needed, especially ifthe casting paper is subjected to more than one use cycle.

In the casting process, the surface of the final substrate 30 becomescoated with the thermoplastic polymer 28 and the thermoplastic polymer28 retains the shape imparted to it by the casting paper 18. Thus, thecasting paper 18 becomes a template to transfer patterns to the finalsubstrate 30. In this use, the patterned release coating must releasethe thermoplastic material, and must be heat resistant in order toretain its shape under heat and pressure, thus imparting the shape orpattern to the final substrate. The durability of the highly crosslinkedcoatings containing the cured acrylic acid esters of fatty alcohols, asecond cured monomer and, optionally, a cured resin, is highly desiredin this use.

In another embodiment, the release sheet 18 shown in FIG. 2 can beutilized to form a smooth and/or glossy surface on the substrate. Assuch, the surface 17 of the release coating 16 can be substantiallysmooth (e.g., conforming to the first surface 24 of the base sheet 16).In this embodiment, the smoothness of the base sheet 20 used in castingrelease materials can be critical, especially if the casting material isto be used to impart a smooth or glossy surface. As a general rule, itis easy to understand that the first surface 24 of the base sheet 20should be about as smooth or smoother than the smoothness desired in thefinal coated substrate 20. Surface smoothness can be measured by variousmethods. One method is the Sheffield method. In this method, a circularrubber plate or gasket with a hole in the center is applied with aspecified pressure to the substrate. Air is forced under a specifiedpressure into the center hole and the air flow resulting from airescaping from under the gasket is measured. The higher the air flow,measured in milliliters per minute, the rougher the substrate. For manycasting applications, papers such as clay coated papers with Sheffieldsmoothness less than about 100 are smooth enough, while very finecastings may require smoother substrates with Sheffield smoothness ofaround 10 or less. Base sheets with patterns such as embossed basesheets are also useful since, after release coating, they can be used toimpart patterns to the final substrate.

Casting papers as described above can also be used to impart patternedsurfaces to thermoplastic materials, such as PETG panels. (PETG is aglycol modified polyethylene terephthalate, a hard thermoplastic.) Thepatterned plastic items can then be used for decorative wail panels,furniture surfaces and coverings for instruments, appliances etc. Therelease coatings of FIG. 2, having cured fatty alcohol esters of acrylicacid in a highly crosslinked structure, are very useful in the abovecasting processes due to their release properties, durability and heatresistance.

IV. Heat Transfer Decals

Referring to FIG. 8, a heat transfer decal 40 is shown having an image41 applied to the release coating 16 on the base sheet 20 of the releasesheet 18 of FIG. 2. The image 41 may be white or colored, and melts orbecomes tacky when heated, thus adhering to a desired substrate (e.g., afabric, such as a garment). The decal image 41 can contain a dye orpigment, a polymer and optionally a plasticizer. For example, it may bea colored polyvinylchloride plastisol or pigmented polyurethane.

The image 41 is preferably applied with a silk screen but other methodsof application can be employed, including but not limited to,flexographic printing and offset lithography. Screen printing is oftenused to apply polyvinylchloride plastisol images, as is known to thoseskilled in the art. These plastisols are dispersions of apolyvinylchloride resin in a plasticizer which are liquids when appliedbut which solidify when heated due to interaction of the resin andplasticizer when the heat softens the resin. For example, thepolyvinylchloride image 41 can be applied to the release surface 17 ofrelease sheet 18 of FIG. 2 and heated to solidify the plastisol.

Subsequently, the decal 40 can be pressed onto a substrate 30 using heat(H and pressure (P), resulting in transfer of the decal image 41 to thesubstrate 30, as depicted sequentially in FIGS. 9 and 10.

Alternatively, the decal 40 can be printed via a flexographic, silkscreen or other well known printing method as a coating 41 of pigmentedor dyed resin such as a polyurethane resin dispersed in water ordissolved in an organic solvent. After drying, the decal is not tackyuntil it is heated and thus can be used when desired to transfer theimages with heat and pressure to substrates 30 such as leather orgarments.

In these heat transfer decals, as is well known to those skilled in theart, the image 41 is applied in the form of a mirror image, whichbecomes a “right reading” image after transfer. Also, in the usesdescribed above, the release coating of FIG. 2 provides a printablerelease surface for the heat sensitive decal inks due to its relativelylow critical surface tension (compared to siloxane coatings) whichallows for good wetting of the surface. Also, this highly crosslinkedcoating containing the cured acrylic acid ester of a fatty acid, thecured second monomer and the desired cured resin provides release of thedecals even after heating to temperatures of 375° F. or higher.

V. Printable Heat Transfer Papers

Referring to FIG. 11, heat transfer sheet 50 is shown having a printableheat transfer coating 52 overlying the release surface 16 of the releasesheet 18 of FIG. 2. The printable heat transfer coating 52 may befashioned to be printable by a variety of methods including but notlimited to ink jet printing, laser printing and offset lithography. Whensubjected to heat and pressure, the printable heat transfer coating 52melts and adheres to materials to which it is pressed against, such asfabrics, leather, wood and other materials or other articles which arenot conveniently printed by conventional techniques.

FIG. 12 shows an image 54 printed onto the printable heat transfercoating 52 of FIG. 11. Generally, the image 54 printed onto the printcoating is a mirror image of the image which will be formed in the finalsubstrate 30. One of ordinary skill in the art would be able to produceand print such a mirror image using any one of many commerciallyavailable software picture/design programs. Due to the vast availabilityof these printing processes, nearly every consumer easily can producehis or her own image to make a customized textured image on a substrate.

FIGS. 13 and 14 sequentially depict transfer of the image 54 and theprintable heat transfer coating 52 to a substrate 30. The printable heattransfer coating 52 is meltable in order to adhere to the finalsubstrate 30 after applying it with heat and pressure. Such printcoatings can be fashioned to be printable via, for example, laserprinting and ink jet printing. Such heat transfer papers are designed tobe “cold peelable”, which means that the paper can be removed after thesubstrate and paper are cooled. These heat transfer papers are wellknown to those skilled in the art. See, for example, U.S. Pat. Nos.4,863,781, 6,033,739, 6,113,725 and 6,450,633. The present inventionextends this technology further by providing durable, heat resistantrelease coatings 16 which release a wide variety of polymers includingacrylic polymers and polyurethanes; yet, due to the relatively highcritical surface tension of the cured coatings, can be coated withprintable heat transfer coating 52 having surface tensions lower thanabout 32 dynes per centimeter. For example, the release coatings 16 canbe printed with solvent borne coatings in solvents having surfacetensions below about 32 dynes per centimeter or with water basedcoatings having surfactants which reduce the surface tension of thecoatings to less than about 32 dynes per centimeter. Thus, heattransferred images on substrates 30 such as fabric and leather whichpossess desired properties offered by acrylic and polyurethane polymerssuch as stretch-ability, softness and durability can be created.

VI. Erasable Materials

The release substrate of FIG. 1 can be adapted to serve as an erasablematerial, such as an erasable poster board, erasable tablet, erasablecoloring book and a portion of an erasable game. In this use, inks withsurface tensions below about 32 dynes per centimeter can be used toapply images which retain their shape due to the relatively highcritical surface tension of the coated substrate; yet, most inks can beeasily erased due to the release and durability properties of therelease coating. Substrates such as films and papers can be adapted tothe desired use. Examples include thin paper substrates for tablets,heavy paper boards for posters and tacky films for adhesion of theerasable films to walls. For some uses, including coloring books andgame boards, a non-erasable image as a background image which remainsafter each erasure is needed.

Several methods of applying such background images may be used. Oneexample is the printed erasable substrate depicted in FIG. 15; in whichthe substrate 12 is printed with a background image 41, and then therelease coating 16 is applied over the printing. The image 41 candefine, for some examples, an image for coloring, a game board, a maze,a “connect the dots” image etc. After use (coloring or marking) thecoloring or marking can be erased repeatedly, giving a fresh start forfurther coloring, drawing or gaming. The printing 41 under the releasecoating 16 remains after erasing. It is understood that any type ofprinting which can be successfully used on a given substrate could beused in this adaptation, since the substrate is printed before releasecoating 16.

A second method of making the background printed erasable paper isdepicted in FIG. 16, in which the image 41 is applied as a mirror imageto one side of a translucent substrate 60 (e.g., a translucent film orpaper) and the release coating 16 is applied to the opposite side. Theimage 41 can be viewed as a “right reading” image from the releasecoated side. As such, coloring, gaming marks etc. can be applied to therelease coating 16 and erased repeatedly without affecting the printingon the other side. A convenient advantage to this construction is thatthe image 41 can be applied after the substrate 60 is release coated,as, for example, might be done if one wishes to create a game using handdrawing or a small printer.

A third method of applying durable printing to the erasable material iswith dye sublimation transfer printing. In this method, the releasecoated substrate 18, as shown in FIG. 2, is pressed with heating to apaper which has been printed with a sublimable dye image. The sublimabledyes diffuse into the release coating 16 and, since the dyes aredissolved in the coating, they cannot be erased from the surface.

VII. Heat Activated Protective Film.

In FIG. 17, the release coating 16 is disposed on one side of a meltableadhesive film 65 to form a protective film 64. Meltable adhesive films65 are known to those skilled in the art of laminating and in themanufacture of adhesives. For example, Lenderink Technologies ofBelmont, Mich. offers a variety of these films. FIG. 18 depictsapplication of the protective film 64 to a substrate 30 utilizing heat Hand pressure P to adhere the release coating 16 to the substrate 30 viathe meltable adhesive film 65 therebetween. The protective film 64 canthus protect the substrate 30, which can be cloth, leather, wood, wallpanel, furniture items and many others. Since most inks, paints andadhesives can be easily removed from release coating 16, the substrates30 are protected from graffiti, food stains, paint, inks etc.

EXAMPLES

The initial formulations for release coatings were mixed and thenapplied by hand to 8.5×11 inch sheets of Neenah Paper Duraform LabelStock using a #3 wire wound rod, which gives approximately 6 microns ofcoating. The coated sheets were attached to a carrier web and then curedon a pilot electron beam curing line at PCT Engineered Systems, LLC. Thecarrier web was a roll of woven fiberglass cloth. The dosage was 4.0megarads at 150 kilovolts under a Nitrogen atmosphere with less than 200parts per million of Oxygen. (A Nitrogen atmosphere is used to eliminatemost of the Oxygen, which can inhibit cure in electron beam curing.) Therelease coating compositions are given in Table 1. Scotch 810 tape pulltests, Gorilla Tape pull tests and two part epoxy pull tests are givenin table 2. For reference, Gorilla Tape, (from The Gorilla Glue Company,Cincinnati, Ohio) is much more aggressive (adheres more strongly) thanScotch 810 tape and the two part epoxy adhesive (Perma Poxy-5 minuteepoxy from PermaTex) is even more aggressive. The Scotch 810 tape wasapplied by hand and then pulled off to subjectively judge the ease ofrelease. The Gorilla Tape pulls were done in the same manner and allpulls were harder due to stronger tape adhesion. If some of the coatingcame off with the tape, the portion of coating removed from the paperwas noted. The two part epoxy was mixed, applied in an area about thesize of a nickel, allowed to cure for at least five minutes and removedby flexing the paper near an edge of the epoxy coating to loosen anedge, then holding the paper flat on a lab bench while the coating waspulled off. Then the percentage of coating removed from the coated areawas estimated.

TABLE 1 Initial candidate release coating formulations. Ingredient(percent) A B C D E F G H I J K L Ebecryl 40 40 40 40 40 40 40 40 40 4040 40 3700-20T TMPTA 60 59.5 50 50 45 40 50 45 40 SR9003 50 50 44.5SR335 5 5 5 20 Byk 307 0.5 0.5 Tego Rad 10 10 2500 Tego Rad 10 10 10 1020 2600 Tego Rad 10 10 2700 Notes on Raw Materials: A. Ebecryl 3077-20T(Cytec) is an acrylated bisphenol A epoxy oligomer. The 20T designationmeans the oligomer is diluted with 20% TMPTA monomer. B. TMPTA (cytec)is trimetholyl propane triacrylate. C. SR9003 (Sartomer) is propoxylatedneopentyl glycol diacrylate. D. SR335 (Sartomer) is lauryl acrylate. E.BYK 307 (Actega) is ethyoxylated or propoxylated polydimethyl siloxane.F. Tego Rad 2500, 2600 and 2700 are acrylated silicones.

TABLE 2 tape and epoxy resin pull tests on release coated samples.Scotch 810 Two Part Tape Release Gorilla Tape Release Epoxy Release ATight Peel Some Coating Removal Complete Coating Removal B Tight PeelSome Coating Removal Complete Coating Removal C Tight Peel Some CoatingRemoval Complete Coating Removal D Tight Peel Almost No Coating RemovalComplete Coating Removal E Tight Peel Almost No Coating Removal 75%Coating Removal F Less Tight Almost No Coating Removal 50% CoatingRemoval Peel G Easy Peel Almost No Coating Removal 15% Coating Removal HEasy Peel No To almost No Coating 10-20% Coating Removal Removal I TightPeel Almost No Coating Removal 50% Coating Removal J Easy Peel Almost NoCoating Removal Complete Coating Removal K Easy Peel No To almost NoCoating 10-20% Coating Removal Removal L Easy Peel Some Coating removal10% Coating Removal

The test samples A through L were tested for use as casting substratesfor water based polyurethanes, acrylic latex and plasticized PVC latexand also, as forming substrates for PETG plastic. The results aresummarized in Table 3. In this table, PUD is polyurethane dispersion.PUD 1 is Sancure 2710 from Noveon; PUD 2 is Witcobond W 296 fromChemtura; PUD 3 is Permax 230 from Noveon; PVC is Vycar 578, plasticizedPVC from Noveon and “Acrylic” is Rhoplex B20, a soft acrylic latex fromRohm and Haas. “PETG” is a panel of PETG plastic. The coatings PUD 1, 2and 3, the acrylic latex and the plasticized PVC latex were applied witha wire wound rod to give approximately 45 grams per square meter ofcoating and were dried in a forced air oven. In some cases, the waterbased coating did not wet the release coating well. This was correctedby adding 0.25 grams of Q2-5211, a silicone surfactant from Dow Corning,to the water based coating. After drying, the release of these coatingswas tested by pressing the latex coated sample onto a piece of 100%cotton T shirt material in a heat press for 35 seconds at 375 degreesF., then removing the paper. Release was judged as being “good” if thecoating separated cleanly from the release coating onto the clothwithout removing any of the coating from the cloth and without removingany release coating from the paper. One sample rated as “marginal” gavesuccessful transfers if the paper was removed carefully. One samplerated as “tight” gave a successful transfer but it was difficult toremove the paper.

For testing against a PETG panel, the release coated samples werepressed in a heat press for 5 minutes at 275 degrees F. and the paperwas removed after cooling. Samples were judged as having good release ifthey peeled easily from the panel without leaving any coating on thepanel. The sample rated as “marginal” left a small amount of coating onthe panel.

TABLE 3 Release tests of the Initial samples A through L PUD 1 PUD 2 PUD3 ACRYLIC PVC PETG A Not Good Not Good Not Good Not Good Mar- Not Goodginal B Not Good Not Good Not Good Not Good Good Marginal C Not Good NotGood Not Good Not Good Good Not Good D Not Good Not Good Not Good NotGood Good Not Good E Not Good Not Good Not Good Not Good Good Good F NotGood Not Good Not Good Not Good Good Good G Not Good Not Good Not GoodNot Good Good Good H Not Good Not Good Not Good Tight Good Good I NotGood Not Good Not Good Not Good Good Good J Not Good Not Good Not GoodNot Good Good Not Good K Not Good Not Good Not Good** Good* Good Good LGood Good Good* Good* Good Good *Poor Wetting **Poor Wetting, OK withSurfacant added

The initial testing of the samples “A” through “L” indicated that,surprisingly, no silicone containing materials are needed (sample “L”)to provide good release of a variety of materials, includingpolyurethanes, acrylics and PETG. More extensive testing of the “L”coating was carried out; specifically, it was tested on other substratesand it was tested for release of a variety of inks and paints. Thesetests reveal that it is a good candidate coating for erasable productsand for graffiti resistant items. In addition, feasibility ofapplication of coating “L” to a roil of material was demonstrated on apilot scale coater.

Coating “L”, described above, consisted of 40% Ebecryl 3700-20T, anepoxy acrylate; 40% Trimetholyl propane triacrylate and 20% SR 335,which is lauryl acrylate. The paper in this test run was “100 poundSterling Ultra gloss Web Text”, which is a two sided ‘clay coated’publication grade available from New Page Corporation. The paper wascoated at PCT on a pilot line equipped for flexo printing.

Sample #1—Initial tests were done using a 27 bcm anilox roll and asmooth rubber applicator roll with a speed ratio of one to one at a linespeed of 50 feet per minute. Note, the bcm number of the anilox roll isa measure of the volume it can deliver, measured in billion cubicmicrons per inch. Also, it should be noted that the volume of coatingwill be reduced if the anilox roll is run slower than the transfer roll;the transfer roll being the roll which transfers the coating to thesubstrate.)

The cure was done in a Nitrogen flooded atmosphere with less than 200ppm Oxygen. The current voltage was 150 kilovolts with the current at 20miliamps, which gives a dosage of 4 megarads at a line speed of 50 feetper minute. The printed width was 17 inches. This gave a glossy, drycoating which had good release for tape and a Sharpie marker. Thecoating weight was 8 grams per square meter. The coating had a slightpattern thought to be from the anilox roll. Changing the roll speeds torun the anilox roll at 25% of the applicator roll speed gave a smoothercoating with only a trace of streaks. The coating weight was 6 grams persquare meter. Sample 1 was then produced at 50 feet per minute with thisanilox/applicator condition, 150 kilovolts and 4 megarads (20 miliampcurrent).

Sample #2—A double coated version was made. The first coating wasapplied the same as sample 1 above, except that the dosage was reducedto 1 megarad (5 miliamps current). This was to improve spreading andadhesion of the second coating. The second coating was applied to thesingle coated paper using exactly the same conditions as sample 1. Thecombined coating weight was assumed to be approximately 12 grams persquare meter.

The single coated paper, Sample 1 and the double coated paper, Sample 2,were tested with a black chisel point marker, a blue ballpoint pen and aUni Paint oil based marker and these could be wiped off with a drytowel. Sharpie fine point permanent markers in eight colors; black,blue, green, yellow, orange, red, purple and brown were applied and letsit for 24 hours. They were all removed with a dry towel. Four blackspray paints were applied to sheets of samples one and two. These wereValspar Plastic paint, Rust Oleum Gloss Protective Enamel, Rust OleumAppliance Epoxy Enamel and Rust Oleum High Performance Flat Black AlkydEnamel. After 24 hours, all these paints were removable. Light coveredareas were removed by rubbing with isopropanol; heavier areas wereremoved with masking tape.

Samples one and two released easily from PETG panels after pressing for5 minutes at 275 degrees F. The release of Rhoplex B 20, Sancure 2710,Witcobond W296, Permax 230 and Vycar 578 was tested the same as was donewith the hand coated samples and they all released easily after coatingonto the paper and pressing to a T shirt fabric, as described above.Rhoplex B 20 showed signs of poor spreading; this was corrected byadding 0.5 dry parts per 100 parts dry B 20, of Q2-5211, a wettingagent, to the Rhoplex B 20.

Samples one and two were tested for food staining by placing a few dropsof the food on the paper, letting it sit for 24 hours, and then rubbingthe spots off with a damp paper towel. All the food stains could beremoved easily; including coffee, mayonnaise, soy sauce, mustard, redwine, pomegranate juice, vanilla extract, ketchup and olive oil.Lipstick was also easily removed after being on the paper for 24 hours.

Several additional materials were tested on Sample 1 to determinewhether or not they could be removed. These included:

-   -   Crayola Window Mega Markers (green, blue, pink, yellow)    -   Crayola Washable Markers (raspberry, golden yellow, emerald,        azure, copper, plum, primrose, teal)    -   Crayola Classic Markers (yellow, brown, pink, gray, black, blue,        green, orange, red, violet)    -   Fibre-Craft Materials Corp. Foam Markers (green, pink, red,        purple, black, blue)    -   Horizon Group USA Face Paints (blue, yellow, red, green, black,        white)    -   Tulip Fabric Spray Paint (red, yellow, blue, green)    -   Horizon Group USA Glass and Poster Marker (yellow)    -   Wilton Color Mist Food Color Spray (green)    -   Horizon Group USA Sparkly Glitter Glue (red)    -   Cra-Z-Art Washable Watercolors (16 colors)    -   Acrylic Paint (12 colors)    -   Scribbles 3D Paint (Pacific Blue, Crystal)    -   Uni Paint oil-base paint marker (black)    -   Elmer's Painters paint marker (red)        All items were purchased and tested within one week.

Each item was applied to the sheet in a 1″×1″ square (except fabricspray paint, glitter glue, and food color spray) and allowed to sit fora period of one hour, two hours, four hours, six hours, eight hours, and24 hours.

The fabric spray paint, 3D paint, glitter glue, and food color spraywere applied to the sheet and allowed to dry overnight.

All of these additional materials tested could be removed from thecoating with a dry paper towel, with the exception of the fabric spraypaints. Those were removed with isopropyl alcohol. The glitter glue and3D paint could be peeled off in areas with thicker application, andrubbed away with a dry paper towel in thinner areas. However, theElmer's paint marker discolored the sheet after only sitting for onehour.

Additional release coating formulations were L1, L2, L3, M, M1, N and O,as shown in Table 4. These coatings were applied to sheets of the 100lb. Sterling Ultra Gloss paper which was used in the above pilot trials.A number 6 wire wound rod, which gives about 12 grams per square meterof coating, was used. The sheets were attached to a web and cured on apilot line at a speed of 50 feet per minute in a Nitrogen atmosphere,with 4 megarads dosage and 150 Kilovolts. Samples L1 and L2 were clearbefore application. L3 was slightly cloudy. The SR 257, stearylacrylate, is a waxy solid at room temperature and was heated to 60degrees Centigrade before mixing. After cooling, the M and M1 coatingswere cloudy. The N and O coatings were clear after cooling.

TABLE 4 Additional release coating formulations. Ingredient (percent) L1L2 L3 M M1 N O Ebecryl 37-20T 35 30 25 40 45 40 40 TMPTA 35 30 25 40 4540 SR9003 (propoxylated 40 neopentyl diacrylate) SR 257 (stearylacrylate 20 10 20 10 SR 335 (lauryl acrylate) 30 40 50 10

All the samples of Table 4 were dry to the touch after curing. They werebarely affected by 50 MEK double rubs. The Scotch 810 tape releasedeasily from all the samples and Sharpie permanent marker writing waseasily removable from them all. The Unipoint oil based marker releasedwell from all the samples in Table 4 except sample M, which left aslight smudge. All of them released well after heat pressing from thewater based coatings listed in Table 3 (PUD1, PUD2, PUD3, Acrylic andPVC). They also released well in the heat pressing test against the PETGpanels at 275 degrees F.

Printed, Release Coated Erasable Paper:

Sheets of 100 Lb. Sterling Ultragloss Web Text from New page were laserprinted with a grid pattern and also with a “Tic Tac Toe” game grid.These were then coated using a number 6 wire wound rod with formulation“L” above on the printed side. Curing was carried out as in the Table 1description above after taping the samples to a web. The release coatedsheets could then be marked with a Sharpie permanent marker and themarks were erased with a paper towel without any affect on the laserprinting.

Printed, Release Coated, Translucent Erasable Paper:

Sheets of Neenah Paper 28 lb per 1300 square foot UV Ultra II were laserprinted with a mirror image of a drawing for coloring. The printedsheets were then coated on the opposite side with a barrier layer ofRhoplex SP 100, (acrylic latex from Rohm and Haas), at 1.8 lb. per 1300square feet after drying. The barrier coated sheets were then coated onthe barrier coated side using a number 6 wire wound rod with the “L”formulation of Table 1. The sheets were taped to a web and cured asdescribed in the Table 1 description. The release coated sheets couldthen be marked with a Sharpie permanent marker and erased with a papertowel.

Release Coated, Erasable Synthetic Paper.

Sheets of Kimdura FPG 110, a 110 micron thick polypropylene syntheticpaper from Yupo Corporation, were coated with formulation “L” from Table1, using a number 6 wire wound rod and then taped to a web and curedaccording to the Table 1 description. The coating adhered well and wasmarkable and erasable with a Sharpie permanent marker.

Release Coatings with No Curable Resin.

The coatings in Table 5 were applied to Kimdura FPG 110 synthetic paperusing a number 6 wire wound rod. They were then attached to a fiberglasscloth carrier web and then cured in a Nitrogen atmosphere as in thetable 1 description. All the coatings were dry to the touch after curingand were written on with black, red, blue, purple, brown, yellow, greenand orange Sharpie fine point permanent markers and with a blackUniPoint oil based marker. After drying for about ten minutes, the markswere all removed by rubbing with a tissue. All the marks could beremoved except for the red marker on sample “T”, which left a faintstain. When coated samples R, S and T were tested with Scotch 810 tape,some of the coating came off the Kimdura so no further release testswere done.

TABLE 5 Release coatings With No Curable resin Ingredient (percent) R ST TMPTA 80 65 50 Lauryl Acrylate 20 35 50

Release Coated Adhesive Film.

Sheets of Neenah paper grade 9751P0, which have a peelable 1.8 mil thickfilm of an ethylene-acrylic acid/ethylene-methacrylic acid copolymerco-extrusion, were coated with formulation “L” (Table 1), as describedin Table 1. The film with the “L” coating was peeled off the paper andthen applied to samples of a 210 gram per square meter polyester clothin a heat press for 25 seconds at 350 degrees F. This gave a glossy,conformal coating on the cloth which was resistant to a permanent markerstain. A sample of tanned cowhide was also coated in the same manner butthe temperature was reduced to 300 degrees F. to avoid discoloration ofthe leather. This gave a glossy stain resistant coating on the cowhide.

AccuDyne Critical Surface Tension Test.

A sample of paper from the pilot run described above having the coating“L” of Table 1 Was tested with AccuDyne pens from DiversifiedEnterprises. The 30 dyne per centimeter pen wet the surface with novoids. The 32 dyne per centimeter pen wet well and voids slowlydeveloped. Thus, the critical surface tension is about 32 dynes percentimeter.

Dye Sublimation Transfer Printing.

A colored image was printed with an Epson C86 color inkjet printer usingSawgrass Technology sublimation inks. The paper used was Neenah Paper24# Classic Crest. The image was pressed against Sample 1 describedabove, from the pilot trial. This was done in a heat press at 375degrees for 25 seconds. This gave a very vivid image on the Sample 1.There was no tendency for the papers to adhere when heated. The imagecould not be removed by rubbing with a paper towel.

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

What is claimed:
 1. A method of forming a release sheet, the methodcomprising: coating a first surface of a base sheet with a releasecoating, wherein the release coating comprises a fatty alcohol ester ofacrylic acid and a curable monomer; curing the release coating while incontact with a forming surface such that a patterned release surface isimparted into the release coating; coating a thermoplastic layer ontothe patterned release surface; positioning the thermoplastic layeradjacent to a substrate; heat transferring the thermoplastic layer tothe substrate; and removing the release sheet from the substrate.
 2. Themethod as in claim 1, wherein the release coating comprises the fattyalcohol ester of acrylic acid in an amount of about 5% by weight toabout 35% by weight.
 3. The method as in claim 1, wherein the fattyalcohol ester of acrylic acid comprises lauryl acrylate.
 4. The methodas in claim 1, wherein the release coating is substantially free fromcompounds having siloxane groups.
 5. The method as in claim 1, whereinthe release coating is substantially free from siloxanes.
 6. The methodas in claim 1, wherein curing the release coating comprises exposing therelease coating to e-beam radiation.
 7. The method as in claim 1,wherein the curable monomer comprises trimethylolpropane triacrylate. 8.The method as in claim 1, wherein the release coating further comprisesa curable polymeric resin.
 9. The method as in claim 8, wherein thecurable polymeric resin comprises an epoxy acrylate polymer.
 10. Themethod as in claim 8, wherein the release coating comprises the curablepolymeric resin in an amount of about 25% to about 60% by weight. 11.The method as in claim 8, wherein the release coating comprises thecurable monomer in an amount of about 25% to about 60% by weight.
 12. Amethod of forming a release sheet, the method comprising: coating afirst surface of a base sheet with a release coating, wherein therelease coating comprises a fatty alcohol ester of acrylic acid and acurable monomer; curing the release coating while in contact with aforming surface that a patterned release surface is imparted into therelease coating; heating a thermoplastic surface on a substrate;pressing the patterned release surface onto the thermoplastic surface;and removing the release sheet from the thermoplastic surface.
 13. Themethod as in claim 12, wherein the release coating comprises the fattyalcohol ester of acrylic acid in an amount of about 5% by weight toabout 35% by weight.
 14. The method as in claim 12, wherein the fattyalcohol ester of acrylic acid comprises lauryl acrylate.
 15. The methodas in claim 12, wherein the release coating is substantially free fromcompounds having siloxane groups.
 16. The method as in claim 12, whereincuring the release coating comprises exposing the release coating toe-beam radiation.
 17. The method as in claim 12, wherein the curablemonomer comprises trimethylolpropane triacrylate.
 18. The method as inclaim 12, wherein the release coating further comprises a curablepolymeric resin.
 19. The method as in claim 18, wherein the curablepolymeric resin comprises an epoxy acrylate polymer.
 20. The method asin claim 18, wherein the release coating comprises the curable polymericresin in an amount of about 25% to about 60% by weight.